import random

def pr_normal_chat(n):
    hits = [0] * 20
    for i in range(n):
        x = random.normalvariate(100,30)  # 这里指平均值100，标准差30
        j = int(x/10)
        if 0<= j <20:
            hits[j] += 1
    for i in hits:
        print('*' * int(i * 320 /n))

pr_normal_chat(199000)


